1. Field of the Invention
The present invention relates to a combination clothing washer and drier apparatus. More specifically, the present invention relates to a clothing drier that incorporates the use of solid phase desiccants such as molecular sieves or silica gel to remove water from the drying air, the drying air being recirculated through the apparatus.
2. Description of the Prior Art
Clothing washers and driers are well known in the art. Given the desire to save space, there is increasing interest in combination washer and drier systems, wherein a single rotating drum is utilized for both the washing of clothing and drying of the clothing in one unit. However, since most prior art clothing driers pull surrounding air into the drier that is then heated, passed over the wet clothing where water is transferred to the hot air, and the air then vented to the outside, an external air vent is thus required. This method not only requires a vent pipe to the outside, it requires air to be flowing into the building or dwelling containing the drier. This requires continuous cooling or heating of the replacement air by the air conditioner or heater in the building. This extra air cooling or heating is expensive. Further, the drying time and efficiency is limited by the amount of external air that can be pulled into the drier.
Convenience for household use is gained by replacing the entire washer and drier system into a ventless system that uses the same volume of air in the entire drying process. This is typically accomplished in one combination washer/drier unit, such as that marketed by EQUATOR Corporation (Houston, Tex.). The lint taken up from the drying clothing is absorbed by a spray of water through the heated air coming from the clothing, thus trapping the lint in the cooling water and then discharging the water from the unit. However, the problem with this ventless system is that the drying time is impractically longxe2x80x94from two to three hours. This is because the mister only removes some of the moisture in the hot air by condensation, but still leaves some of the moisture in the air only to be heated and passed back over the clothing to be dried. And, while increasing the air flow may improve the drying time, this also necessitates an increase in the misting to the point of being impractical to achieve the desired drying time because of the large amount of misting water required.
It is desirable in a ventless washer-drier system to have an alternative method of drying the heated, moisture laden air from the clothing that does not rely entirely on the mister sprayer. Desiccants, and in particular, solid desiccants such as molecular sieves, are one alternative. Solid desiccants such as 3A, 4A, and 5A molecular sieves and silica gel can selectively adhere water molecules to the surfaces and interiors of the lattice structure. These desiccants have been used to dry air in applications such as in Larsson (U.S. Pat. No. 4,581,047), who discloses a method of using a solid desiccant in a compressed air line to dry the air, the desiccant being in the form of a cartridge that is replaced once the desiccant has reached adsorptive capacity. However, it is desirable to regenerate the desiccant and thus re-use the same desiccant many times, especially in residential washer and drier units. Reversible removal of the adsorbed water is necessary to make the use of solid desiccants practical in a washer-drier system that is to be used repeatedly in an economical manner. This is typically accomplished by passing relatively dry air over the desiccant while heating the desiccant, as, for instance, is disclosed by Shultz (U.S. Pat. No. 4,023,940).
There are several other methods of regenerating or xe2x80x9cchargingxe2x80x9d solid desiccants. A simple, rechargeable silica gel solid desiccant is disclosed by Peace in U.S. Pat. No. 4,756,726. Another is disclosed by Inglis et al. (U.S. Pat. No. 4,805,317), which uses microwave irradiation of the sieves to drive the water off. Meckler (U.S. Pat. No. 4,887,438) discloses a desiccant assisted air conditioner that uses hot air from the cooling condenser to heat and charge the desiccant. Finally, McFadden (U.S. Pat. No. 5,373,704) uses desiccants in a dehumidifier for home use, the desiccant being regenerated by regenerative air heated by such means as an electric heating coil or natural gas. All of these prior art methods employ the use of air or heated air passed over the moist desiccant that is supplied by external air.
A combination washer-dryer that uses the same volume of air to dry clothing (hence, ventless) through the use of solid desiccants has not been disclosed. There is a need for a practical to use washer and drier combination that has no vent, thus allowing more convenient use in apartment or condominium dwellings. Further, there is a need for a combination washer-drier that operates efficiently and has a reasonably short drying time for the clothing. The present invention is directed towards such use.
It is therefore one object of the present invention to provide a combination washer and drier apparatus for washing clothing and other water-washable articles.
It is another object of the present invention to provide a combination washer-drier apparatus that is made ventless by utilizing the same or substantially the same volume of air during the drying cycle.
It is yet another object of the present invention to provide a solid desiccant clothes drying system that can be re-used by being dehumidified during the wash cycle of the apparatus.
These and other objects of the present invention are achieved by providing a combination closed-circuit washer and drier apparatus having a washing cycle and a drying cycle. The apparatus comprises a unitary housing having a tub and a tumbler within the tub, the tub also having an air inlet and air outlet which allows air to flow through the tub, wherein air flowing from the air inlet is in communication with the tumbler. The apparatus also includes a desiccant charging system located within the unitary housing having a entrance and an exit, the entrance coupled to the air outlet and the exit coupled to the air entrance, thus allowing a continuous flow of air through the system. The desiccant charging system also includes a diverting valve that directs the flow of air primarily through the desiccant system in a closed-loop during the wash cycle. The diverting valve alters the air flow between the washing cycle (desiccant regeneration) to the drying cycle (desiccant water adsorption).
The desiccant charging system has a solid desiccant packed within a desiccant housing, typically molecular sieves of a pore diameter of between about 3 and 5 Angstroms. The desiccant housing typically has a thickness that is at least twice as long as the length to increase the adsorption efficiency. Further, the desiccant charging system includes a dehumidification means, wherein the dehumidification means can be a heating coil, a vacuum apparatus, a microwave generator, or any combination of these. In yet a third embodiment, the desiccant charging system has a water mist spray apparatus to facilitate the removal of water from the air flow during the washing and drying cycles.
Additional objects, features and advantages will be apparent in the written description which follows.